Introduction to SORIT Valves

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Introduction to SORIT Valves

By Bryan Orr

March 8, 2025

There are many brands and styles of evaporator pressure regulating valves (EPR), but none as common as the Parker/Sporlan SORIT and ORIT valves.

Photo Courtesy of Parker/Sporlan

The diagram above clearly shows some of the common applications. An EPR or “hold back” valve maintains a set suction line pressure and, therefore, coil temperature. That is critical in situations where multiple evaporators of different design temperatures connect back to a shared suction header, common in grocery store refrigeration.

The EPR valve “holds back” pressure in the evaporator to a set pressure so long as there is a pressure differential between the evaporator coil and the shared suction header. The suction header must have a LOWER pressure than the lowest design pressure of any evaporator connected to it.

A SORIT valve is an EPR valve or ORIT (Open on Rise of Inlet Pressure) valve that also includes a solenoid stop. The purpose of the solenoid stop is to prevent the defrost gas from entering the suction line and overheating/overloading the compressors when the defrost solenoid opens and back feeds the evaporator to defrost.

For a full and detailed explanation of ORIT and SORIT valves, you can read BULLETIN 90-20 from Parker/Sporlan.

—Bryan

P.S. — Matthew Taylor with Kalos Services made an entire video series about parallel racks, and Part 12 covers EPRs and SORIT valves. You can watch it at https://hvacrschool.com/videos/rack-refrigeration-cycle-part-12-epr/. His 6th Annual HVACR Training Symposium presentation was also about EPRs and how they affect the entire rack. Learn more about the symposium or purchase your virtual ticket at hvacrschool.com/symposium.

#EPR #HOLD BACK #ORIT #SORIT

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The role of confidence-building in safety and long-term success
Starting simple with diagnostic exercises and building complexity gradually
Using field feedback and peer comparison as motivational tools
The cost and commitment required to run effective cohort training programs

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